1. Field of the Invention
This invention is concerned with an improved process for catalytic conversion of a hydrocarbon or an oxygenated compound feed, during which process the catalyst is exposed to steam and hydrocarbons. It is particularly concerned with the catalytic conversion of lower alcohols and ethers to hydrocarbons and steam utilizing, as stabilized catalyst, cobalt-impregnated ZSM-5, for example.
2. Description of the Prior Art
A remarkable growth in the production of synthetic fibers, plastics and rubber has taken place in recent decades. This growth, to a very large extent, has been supported and encouraged by an expanding supply of inexpensive petrochemical raw materials such as ethylene, benzene, toluene, and xylenes. Side by side with this remarkable development, there has been an increasing demand for aromatic hydrocarbons for use as high octane gasoline components. Environmental factors which limit the lead content of gasoline are likely to aggravate the need for aromatics.
Burgeoning demand for olefins, particularly ethylene, and for aromatic hydrocarbons, has of course led to periods of shortage, either due to short supply of suitable feedstocks or to limited processing capacity. In any case, it would appear desirable to provide sufficient means for converting raw materials other than petroleum to olefins and aromatic hydrocarbons.
U.S. Pat. Nos. 3,894,106, 3,894,107 and 3,907,915, respectively, disclose the conversion of alcohols, ethers, carbonyls, or mixtures thereof to higher carbon number hydrocarbons by contact with a catalyst comprising a crystalline aluminosilicate zeolite having a silica to alumina ratio of at least about 12 and a Constraint Index of about 1 to 12.
The conversion of methanol and dimethyl ether to hydrocarbon is described in U.S. Pat. No. 3,911,041.
All of the foregoing patents are herein incorporated by reference for background, and they illustrate recently developed art for efficiently converting oxygenated compounds to hydrocarbons and steam. In each of these patents a novel type of catalyst, exemplified by ZSM-5, is used. This novel type is characterized by unusual thermal stability and resistance to degradation by steam. Nonetheless, with protracted use of such catalyst for reactions which inherently form steam, loss of catalytic activity does occur which is not recoverable by burning in air or by other recognized techniques for regeneration.
Catalytic conversion of hydrocarbons in the presence of hydrogen sulfide or of sulfur compounds is described in U.S. Pat. Nos. 3,173,855 issued Mar. 16, 1965 and 3,175,967 issued Mar. 30, 1965 to Miale et al.
It is an object of this invention to provide a novel long-lived catalyst resistant to irreversible deactivation by steam. It is a further object of this invention to provide a catalytic process for the conversion of oxygenated compounds to hydrocarbons and steam with provision for regenerating the catalyst. It is a further object of this invention to provide a process for the conversion of alcohols, ethers, carbonyl compounds, or mixtures thereof, to higher carbon number hydrocarbons by contact with a catalyst comprising a crystalline zeolite having a SiO.sub.2 /Al.sub.2 O.sub.3 ratio of at least about 12 and a Constraint Index of about 1 to 12 with minimal irreversible loss of catalytic activity. It is a further object of this invention to provide a process for converting oxygenated compounds to hydrocarbons and steam by catalytic contact with a regenerable cobalt-exchanged zeolite catalyst. These as well as other objects will become apparent on reading this entire specification including the claims.